Rzepczynski was happy with his pitch, but Moore poked it to right field and both runners scored easily.
Johnson doesn't usually play small ball but opted for the bunt because Espinosa struck out three times earlier against Wainwright.
"I'm kind of from the Earl Weaver school, just keep swinging," Johnson said. "Don't like to steal that much, either. I don't like to give up outs."
Wainwright became the first Cardinals pitcher to reach double digits in strikeouts in the postseason since Bob Gibson also fanned 10 to beat the Tigers in Game 4 of the 1968 World Series.
Wainwright was a 14-game winner coming off reconstructive elbow surgery that sidelined him all of 2011, with 10 of the wins coming at home. He's been a postseason ace with a microscopic 0.77 ERA and 32 strikeouts in 23 1-3 innings.
He also fanned Harper and Ryan Zimmerman twice each.
"My fastball command kind of left me at the end," Wainwright said. "For the most part I felt like I went out there and competed my tail off. Gave it everything I had."
Gonzalez allowed just one hit in five innings, Freese's full-count bouncer between third and short to start the fourth. But he had trouble finding catcher Kurt Suzuki's glove and keeping warm.
"I kept blowing in my hand, kept looking to do whatever I could to throw a strike," Gonzalez said.
The second inning was his shakiest, when he allowed the Cardinals to score twice and take the lead without a hit. Gonzalez walked four of the first five hitters, putting St. Louis in position to score one run on a wild pitch and a second on Jon Jay's bases-loaded sacrifice fly.
"The whole time I was just saying minimize the damage because things were spinning out of control," Gonzalez said. "I just wanted to match everything Wainwright did. I was trying to keep up with him."
Nationals right fielder Jayson Werth robbed Daniel Descalso of a two-run homer off with a leaping catch to keep it at 2-1 in the sixth. Descalso had a fielding gem of his own in the seventh, ranging far to his left to glove Harper's grounder and then throwing him out by a few steps.
NOTES: The Cardinals went 0 for 8 with runners in scoring position. ... Garcia was 4-2 with a 2.82 ERA in nine starts at home. The lefty has a 2.48 career ERA at Busch. ... Gonzalez also walked seven on June 11, 2011, when he was with Oakland against the White Sox. ... Kozma committed one error in 26 games after taking over as the regular SS in September for injured Rafael Furcal.